Project Summary. The investigators propose a supplement to an ongoing study investigating the relationship of air pollution and birth defects. The supplemental project will address other pregnancy outcomes in order to address emerging questions regarding the full spectrum of health impacts of ambient air pollution on the developing fetus. Recent reports suggest that urban air pollution may be associated with preterm birth, intra-uterine growth retardation and low birth weight. To assess these hypotheses, the investigators will assemble a cohort of all births and fetal deaths occurring among residents of the five- county metropolitan Atlanta area for the period 1994-2004, using vital records data from the Georgia Division of Public Health. Ambient air quality data, including intensive monitoring data available from 1998 forward, will be examined in relation to the occurrence of preterm birth, intrauterine growth retardation and low birth weight in the cohort. Pollution exposures will be characterized using speciated particulate matter and gaseous measurements, source apportionment and near-roadway traffic impacts. Time series analyses will be performed, as well as selected spatial-temporal analyses. With an expected cohort of 550,000 pregnancies, the study will be the largest study of this question to date. The study will have excellent power to observe modest associations of pollutant levels with these outcomes, and use more refined characterizations of pollution than previously available. The supplemental study will be accomplished efficiently with minimal additional resources, taking advantage of ongoing data collection and analysis activities, institutional collaborations, and expertise developed for the existing birth defects project and other air pollution epidemiology studies being performed by the investigators. The resulting study will constitute the most comprehensive assessment to date addressing these important public health questions. Relevance. A growing body of evidence suggests that the developing fetus may be particularly susceptible to adverse effects of ambient air pollution. Given the high level of morbidity and mortality associated with the adverse birth outcomes of prematurity and low birth weight, even small increases in these outcomes translate into substantial public health costs. Identification of risk factors for these outcomes may provide insight into biological mechanisms and contribute to the development of effective intervention strategies. [unreadable] [unreadable] [unreadable] [unreadable] [unreadable]